Klebsiella

Carbapenem resistance is mainly mediated by carbapenemases or extended-spectrum β-lactamases (ESBL) plus a loss of porins. However, we have identified a Klebsiella pneumoniae clinical isolate that contains neither carbapenemases nor ESBLs.

Twenty-three Klebsiella pneumoniae (blaDHA-1) clinical isolates exhibited a range of susceptibilities to LYS228, with MICs of ≥8 μg/ml for 9 of these. Mutants with decreased susceptibility to LYS228 and upregulated expression of blaDHA-1 were selected from representative isolates.

We tested ceftazidime-avibactam and colistin against 24 carbapenem-resistant Enterobacteriaceae (CRE) isolates by time-kill studies. Ceftazidime-avibactam at 0.25×, 1×, and 4× the MIC was bactericidal against 8%, 21%, and 88% of the isolates, respectively.